http://www.allaffiliatepro.com/affiliate-program-software/index.html, you'll find it under the affiliate program type section
I think in that case, they could have said "etc" instead of "Pay Per Anything you want". In response to your second question, it's typically the merchant who dictates the terms, and as a publisher you find a merchant with terms you're willing to accept. Some cases vary, for example if a merchant specifically wants to advertise on your site. In that case, the publisher would probably dictate the terms and the type of program that would be run. I'm not aware of any merchant in particular that will pay "per anything you want", and to get those terms, you'd almost certainly have to be dealing with a merchant that specifically wants to advertise through you and/or your site.